Doosan Upgrades the DL420 Wheel Loader

June 20, 2012

Doosan announced a number of enhancements to accompany interim Tier 4 (iT4) compliance on the Doosan DL420 wheel loader. This 5.5-cubic-yard wheel loader boasts a breakout force of 47,210 pounds, a full-turn tipping capacity of 35,310 pounds and a rugged design built for a variety of material handling applications — such as quarries, mines, road work and site development.

The DL420 offers operators the ability to set upper and lower limits for both the lift arm and bucket stop positions from inside the cab. This improves cycle times in digging and loading applications, while providing improved control of the lift arm and bucket positions.

For those requiring additional dumping capabilities, the DL420 is also available in a high-lift configuration, extending the dump height 20 inches above the standard DL420, to 12 feet, 1 inch.

The new automatic reversing cooling fan can be set to run in reverse to assist in keeping the cooling system clean. The operator can select to reverse the fan via a switch, or it can be set to automatically reverse on a preset time frame. Each time the fan reverses, it will run in reverse for few minutes to clean the cooling system. This helps in dirty and dusty conditions to keep the machine running at optimal performance, using less power to cool the machine. This results in longer working hours and shorter maintenance time to clean the cooling system.

As an alternative to the standard limited slip differential, the DL420 offers an optional hydraulic locking front differential. Based on ground conditions, the operator can choose to lock the differential manually with a floor-mounted foot switch, or allow the machine to automatically engage the system, providing increased driving power when one wheel spins or loses traction and improving machine performance when navigating tough terrain.

Another common option for the DL420 is a torque converter lockup clutch. This enables the machine to climb grades easier and faster, increasing productivity as much as 20 percent in certain stockpiling applications, while also providing a five-gear transmission instead of the standard four-gear setup.

The DL420 horsepower has been increased to 354 with a 6-cylinder diesel engine that has been optimized for use with selective catalyst reduction (SCR) and diesel exhaust fluid (DEF) to comply with iT4 emission regulations. Engines with this configuration are optimized to reduce particulate matter (PM) by operating at higher combustion temperatures and to reduce nitrogen oxides (NOX) with exhaust after treatment using SCR technology. Additionally, engines using SCR systems offer increased fuel efficiency ─ as much as 16 percent on this machine ─ due to the engine optimization, which allows for a more complete fuel burn.

The new auto-idle feature provides additional noise reduction and fuel savings by reducing the working idle of the wheel loader from 950 rpm to a standby idle setting of 750 rpm when the machine in inactive for 10 minutes.

The 775-cubic-inch engine features a high-pressure common-rail (HPCR) design with direct fuel injection, electronic control and four valves per cylinder. The high-pressure common-rail fuel system increases the efficiency of fuel delivery by increasing the pressure up to 34,000 psi. The increased pressure allows the injector to inject a finer mist into the engine, which results in a more efficient combustion that in turn produces more torque and improved fuel economy, less noise, lower operating costs and cleaner exhaust.

Service intervals on the front lift arm pins have increased 500 percent from 50 to 250 hours, reducing operating costs and downtime. Tilt cylinder hydraulic hoses have been rerouted for improved hose reliability, better hose movement and improved visibility to the attachment.

More new options for Doosan wheel loaders include a diesel-powered coolant heater to improve starting in cold weather or a block heater that warms the engine coolant before engine startup with an electrical heater.

The DL420 is now available with optional electric steering to decrease operator fatigue during repetitive cycle operations on the jobsite. A joystick has been added to the left armrest that allows the operator to control the directional movement without having to use the steering wheel. A new door threshold design makes getting in and out of Doosan wheel loaders — and cleaning the inside of the cab — much easier.

Interior cabin improvements also include a number of multi-function display panel upgrades on a centralized monitor that allows the operator to view comprehensive machine system information. The centralized monitor displays critical machine information — such as engine rpm, engine coolant temperature, fuel level, DEF level, machine warnings and the transmission selected gear. A key exterior cabin improvement is the lower front side glass has been widened, providing improved visibility of operations.

The DL420 — like every new Doosan machine — is covered by a 48-hour parts guarantee. The program guarantees that if a “machine-debilitating” part is needed, Doosan will deliver it directly to the end user within two business days or Doosan will pay for a replacement machine rental.